异常而从控制器发送响应JSP页面

我想送从Spring MVC的控制器，JSP页面的响应，我得到了一个异常异常而从控制器发送响应JSP页面

首先，我试图返回一个列表，以JSP页面

对于列表代码：

@RequestMapping(value = "/Users", method = RequestMethod.POST) 
@ResponseBody 
public List<Users> getUsers(@RequestParam(value = "intermediate" ,required = false) String intermediate)throws java.text.ParseException{ 
    List<Users> list = null; 

    int intermediateSelection = Integer.parseInt(intermediate); 

    list = getUsersBySelection(IntermediateSelection) //This will return list of users 

    return list; 
    }

然后我试图一个JSONObject返回JSP页面

代码的JSONObject：

@RequestMapping(value = "/Users", method = RequestMethod.POST) 
@ResponseBody 
public JSONObject getUsers(@RequestParam(value = "intermediate" ,required = false) String intermediate) throws java.text.ParseException{ 
    List<Users> list = null; 

    int IntermediateSelection = Integer.parseInt(intermediate); 

    list = getUsersBySelection(IntermediateSelection); //This will return list of users 

    Iterator<Users> iterator=list.iterator(); 

    JSONObject UsersJSON = new JSONObject(); 
    JSONArray usersArray = new JSONArray(); 

    while (iterator.hasNext()) { 
     Users users = iterator.next(); 

     JSONObject object = new JSONObject(); 
     object.put("Id", users.getUserId()); 
     object.put("Name", users.getUserName()); 
     object.put("Group", users.getGroup()); 

     usersArray.add(object); 
    } 

    UsersJSON.put("users", usersArray); 

    //System.out.println(UsersJSON.toString()); 

    return UsersJSON; 
    }

他们既没有为我工作。我有这样的例外。

org.apache.catalina.core.StandardWrapperValve invoke 
java.lang.StackOverflowError 
at java.lang.ClassLoader.defineClass1(Native Method) 
at java.lang.ClassLoader.defineClass(ClassLoader.java:800) 
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) 
at org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:2918) 
at org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:1174) 
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1669) 
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1547) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:682) 
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:132) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:94) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:24) 
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:666) 
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:666) 
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:132) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:94) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:24) 
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:666) 
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:666) 
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:132) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:94) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:24) 
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:666) 
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:666) 
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:132) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:94) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:24) 
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:666) 
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:666) 
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:132) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:94) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:24) 
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:666) 
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:666) 
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:132) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:94) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:24) 
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:666) 
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:666) 
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:132) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:94) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:24) 
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:666) 
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:666) 
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:132) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:94) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:24) 
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:666) 
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:666) 
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:132) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:94) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:24) 
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:666) 
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:666) 
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:132) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:94) 
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:24) 
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:666) 
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:666)

用户POJO的：

@Entity 
@Table(name = "Users") 
public class Users implements java.io.Serializable { 

    private int userId; 
    private Role role; 
    private Groups groupId; 
    private UserType userType; 
    private String userName; 
    private String password; 
    private Boolean isActive; 

    public Users() { 
    } 

    public Users(int userId, Role role, Groups groupId ,UserType userType, String userName, String password, boolean isActive) { 
     this.userId = userId; 
     this.role = role; 
     this.groupId = groupId; 
     this.userType = userType; 
     this.userName = userName; 
     this.password = password; 
     this.isActive = isActive; 
    } 

    @Id 
    @GeneratedValue(strategy = GenerationType.IDENTITY) 
    @Column(name = "UserID", unique = true, nullable = false) 
    public int getUserId() { 
     return this.userId; 
    } 

    public void setUserId(int userId) { 
     this.userId = userId; 
    } 

    @ManyToOne(fetch = FetchType.LAZY) 
    @JoinColumn(name = "RoleID", nullable = false) 
    public Role getRole() { 
     return this.role; 
    } 

    public void setRole(Role role) { 
     this.role = role; 
    } 

    @ManyToOne(fetch = FetchType.LAZY) 
    @JoinColumn(name = "GroupId", nullable = false) 
    public Groups getGroup() { 
     return this.groupId; 
    } 

    public void setGroup(Groups group) { 
     this.groupId = group; 
    } 

    @ManyToOne(fetch = FetchType.LAZY) 
    @JoinColumn(name = "UserTypeID", nullable = false) 
    public UserType getUserType() { 
     return this.userType; 
    } 

    public void setUserType(UserType userType) { 
     this.userType = userType; 
    } 

    @Column(name = "UserName", nullable = false) 
    public String getUserName() { 
     return this.userName; 
    } 

    public void setUserName(String userName) { 
     this.userName = userName; 
    } 

    @Column(name = "Password", nullable = false) 
    public String getPassword() { 
     return this.password; 
    } 

    public void setPassword(String password) { 
     this.password = password; 
    } 

    @Column(name = "IsActive", nullable = false, columnDefinition = "BIT") 
    public Boolean isIsActive() { 
     return this.isActive; 
    } 

    public void setIsActive(Boolean isActive) { 
     this.isActive = isActive; 
    } 
}

来源

2015-12-22 Dev

你可以发布'Users.java'类吗？你在那个班有什么关系吗？ – Lucky

查看编辑后的代码.. – Dev

从this blog post，

为杰克逊工作得很好，这种关系的双方一个不应该被序列化，以避免令人烦恼的无限循环，导致我们的StackOverflow错误。

所以，杰克逊为基准的前部，例如一个Java类（即，在用户类别List<Role>角色）的属性，转换它在一个类JSON存储格式;这就是所谓的编组过程。然后，杰克逊寻找参考文献的后半部分（即Role类中的List<User>个用户），并将其保留为，而不是序列化它。这部分关系将在前向引用的反序列化（取消编组）期间重新构建。

解决方案：

添加@JsonManagedReference在关系（即Users.java类）的前部：
添加@JsonBackReference在关系的后部（即Role.java和Groups.java类）：

Users.java（例如代码）：

@Entity 
public class Users implements java.io.Serializable{ 

@Id 
@GeneratedValue(strategy = GenerationType.IDENTITY) 
@Column(name = "UserID", unique = true, nullable = false) 

@Column(name="name") 
private String name; 

@ManyToOne(fetch = FetchType.LAZY) 
@JoinColumn(name = "RoleID", nullable = false) 
@JsonManagedReference 
public Role getRole() { 
    return this.role; 
} 

...

Role.java(example code)：

@Entity 
public class Role implements java.io.Serializable { 

@Id 
@GeneratedValue(strategy=GenerationType.IDENTITY) 
private int id; 

@OneToMany 
@JsonBackReference 
private Set<User> users = new HashSet<User>(); 

...

和以同样的方式也适用于

Groups.java

@Entity 
public class Groups implements java.io.Serializable { 

@Id 
@GeneratedValue(strategy=GenerationType.IDENTITY) 
private int id; 

@ManyToMany(mappedBy="groups") 
@JsonBackReference 
private Set<User> users = new HashSet<User>(); 

...

你可以检查另一个有用的注释是@JsonIdentityInfo：使用它，每次杰克逊序列化你的对象，这将增加一个ID（或另一个属性的选择）它，所以它不会完全 “扫描”它每次。当您在更多相互关联的对象（例如：Order -> OrderLine -> User -> Order和之后）之间有一个连锁循环时，这可能会很有用。

在这种情况下，你必须要小心，因为你可能会需要（与共享同一卖方更多的产品例如在产品列表）不止一次阅读你对象的属性，这注释阻止你这样做。我建议始终查看 firebug日志以检查JSON响应，并查看代码中发生了什么。

希望这会有所帮助。

来源

2015-12-22 07:57:34 Lucky

异常而从控制器发送响应JSP页面

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